Impaired facilitation of self-control cognition by glucose in patients with schizophrenia: A randomized controlled study

• Published in: Schizophrenia research 2014-06, Vol.156 (1), p.38-45
• Main Authors: Leung, Chung-Ming, Stone, William S, Lee, Edwin Ho-Ming, Seidman, Larry J, Chen, Eric Yu-Hai
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Analysis of Variance; Biological and medical sciences; Blood Glucose; Cognition; Cognition Disorders - blood; Cognition Disorders - etiology; Fasting; Female; Glucose - administration & dosage; Hand Strength; Humans; Impulse control; Internal-External Control; Male; Medical sciences; Neuropsychological Tests; Nutrition-based intervention; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Schizophrenia; Schizophrenia - complications; Self Concept; Willpower; Young Adult
• ISSN: 0920-9964; 1573-2509
• DOI: 10.1016/j.schres.2014.03.010

Abstract Objective Studies in healthy individuals show that exerting self-control consumes cognitive resources, which reduces subsequent self-control performance. Restoring the availability of blood glucose eliminates this impairment. Patients with schizophrenia are found to have self-regulatory dysfunctions. This study aims to investigate whether patient's (a) glucose facilitation effects will be impaired, and (b) will have exaggerated depletion in a self-control task. Method 40 patients with schizophrenia-spectrum disorders and 40 normal controls were recruited. A two drinks (glucose vs. placebo) × two depleting phases (self-control depleted vs. non-depleted) between-groups design was used. We examined the blood glucose levels before and after the selfcontrol depletion phase and the subsequent performances in two self-control tasks (handgrip and Stroop tests) after the drink condition. Results The four groups (depleting × glucose, depleting × placebo, non-depleting × glucose and nondepleting × placebo) of both patients and normal controls were comparable on a number of characteristics. The change in blood glucose level in the depleting group was significantly different from those in the non-depleting group. Two × two between-subjects ANOVAs were carried out to test the performances in the handgrip and Stroop tasks. Significant interactions were found in healthy controls regarding both tasks. However, a significant interaction was only found in patients regarding the handgrip task but not the Stroop task. Conclusions This study demonstrated an abnormal glucose facilitation effect in patients during a cognitive self-control task but not during a physical self-control task. The findings also suggested for the first time that a self-control depletion effect is intact in patients with schizophrenia.